Compressed-air pump

ABSTRACT

This invention relates to a compressed-air pump which has a compressed-air motor and operates with compressed air and has a cylinder and a cooperating block or head therefor. A piston moves forward and backward in the cylinder space. The supply of compressed air to the motor is controlled by a valve movable between first and second positions in a bore of the block. The block is formed with passageways for supplying compressed air to the piston when it is in one position in the cylinder space and the valve body is in its first position, and for terminating such supply of compressed air when the valve body moves to its second position responsive to the supply of compressed air. In the second position of the valve body communication is established between the cylinder space and the atmosphere. In order to reduce malfunction of the compressed-air motor all of the compressed air supply passageways are formed in the block and the valve body is characterized by the absence of passageways.

United States Patent 91 Orr [451 Apr. 10, 1973 I54] COMPRESSED-AIR PUMP Inventor: Bengt Erik Orr, Nas, Sweden Assignee: Aktiebolaget Electrolux, Stockholm,

Sweden [22] Filed: Mar. 15, 1971 [21] Appl. No.: 124,188

Foreign Application Priority Data Mar. 13,1970 Sweden .3337/70 [56] References Cited UNITED STATES PATENTS 3/1963 Hunnicutt ..91/290 3/1954 Anderson etal. ..91/290 FOREIGN PATENTS OR APPLICATIONS 277,636 3/1928 Great Britain ..91/290 605,270 11/1934 Germany ..9l/290 Primary ExaminerPaul E. Maslousky Att0rneyEdmund A. Fenander [5 7-] ABSTRACT This invention relates to a compressed-air pump which has a compressed-air motor and operates with compressed air and has a cylinder and a cooperating block or head therefor. A piston moves forward and backward in the cylinder space. The supply of compressed air to the motor is controlled by a valve movable between first and second positions in a bore of the block. The block is formed with passageways for supplying compressed air to the piston when it is in one position in the cylinder space and the valve body is in its first position, and for terminating such supply of compressed air when the valve body moves to its second position responsive to the supply of compressed air. In the second position of the valve body communication is established between the cylinder space and the atmosphere. In order to reduce malfunction of the compressed-air motor all ofthe compressed air supply passageways are formed in the block and the valve body is characterized by the absence of passageways.

12 Claims, 1 Drawing Figure COMPRESSED-AIR PUMP BACKGROUND OF THE INVENTION and second positions in a bore of a cooperating block or head for the cylinder. In one position of the piston compressed air is supplied thereto when the valve body is in its first position. The valve body is moved from its first to its second position responsive to such supply of compressed air to the piston, such movement of the valve body initially terminating the supply of compressed air to the piston and subsequently permitting compressed air to be discharged from the cylinder space to the ambient air or atmosphere. 2. Description of the Prior Art Compressed-air pumps of the kind described above are known. One example of this kind of pump is disclosed in British Pat. No. 9 17,699. In this British patent passageways for compressed air are provided both in the cylinder head or block and the valve body. Since passageways are formed in the valve body it becomes a complicated component of the structure and expensive to fabricate. By reason of the passageways in the valve body and the arrangement of the passageways in the cylinder head or block, there is a tendency for the passageways to clog so that malfunction of the compressed-air motor frequently occurs which is objectionable. Further, by providing a relatively large passageway in one end of the valve body a small bearing surface must be relied upon at the immediate vicinity of such passageway. This is alsoobjectionable for the further reason that it is easily deformed when not handled properly and expensive to replace when it cannot be properly aligned with other components of the compressed-air motor.

SUMMARY OF THE INVENTION It is an object of my invention to provide an improved compressed-air pump which has a compressedair motor in which all of the compressed air supply passageways are formed in the block or head and the valve body is characterized by the absence of such passageways.

Another object of the invention is to provide such an improved compressed-air motor in which malfunction of the motor is reduced to a minimum and a simple fabricated construction is obtained.

I accomplish this, as just explained, by providing a valve body which is characterized by the absence of compressed air passageways. This lends itself to the use of inexpensive materials, such as plastics, for example, in the valve body.

In the preferred embodiment the valve body comprises a rod having an intermediate portion and first and second end portions, the first end portion being removed from the motor piston and the second portion being nearer to the piston. The first end portion includes a resilient member which can be formed of a suitable plastic and is in sealing engagement with the bore of the motor head or block. The second end portion is solid and in sliding engagement with at least av part of the bore. The intermediate portion has a smaller cross-sectional area than that part of the bore with which it coextends.

In a first position of the valve body compressed air can be supplied through a passageway in the motor block directly to the cylinder space. This effects movement of the piston which in turn promotes movement of the valve body to a second position. When this occurs the supply of compressed air to the cylinder space stops and air is discharged from the cylinder space to the atmosphere or ambient air through a path of flow including an exhaust passageway extending to an exterior surface of the motor block from the bore space enveloping the intermediate narrow portion of the valve body.

By providing a valve body in which a resilient .member is employed which is in sealing engagement with the bore of the motor block an accurate fit of the valve body within the motor block is only required at one region instead of at several regions, as required in the prior art British patent, for example. In this way the components of the compressed-air motor can be accurately aligned and rigidly secured to one another.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, the single FIGURE is a vertical sectional view of a compressed-air pump which has a compressed-air motor embodying my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The compressed-air pump embodying my invention includes a motor block 10, a cylinder 11 secured thereto and a pump block 12 secured to the cylinder. The motor block 10 has a bore 13 in which a valve body 14 is movable.

The valve body 14 includes a slide 15, an intermediate portion 16 and a remote end 17 recessed to receive a resilient seal 18. Both the valve body and the resilient seal are preferably formed from suitable plastic materials. As shown in the drawing, the resilient seal includes a conical collar integrally connected to a bushing 19, the outer peripheral portion of the collar bearing resiliently against the inner wall of the bore 13. Due to the design of the seal great manufacturing tolerances can be permitted for the corresponding portion of the bore 13.

The radial extension or cross-sectional area of the intermediate portion 16 is smaller than that of the bore, so that there will be a space 20 between the intermediate portion and the wall of the bore. This space is in communication with the atmosphere through a channel 21.

The slide 15 has a conical-shaped portion 22 to which is fixed a thrust head 23. At its other end, the slide is formed with a flat surface 24 which, as shown in the drawing, engages a flat seat 25. This part of the slide 15 is the only region requiring an accurate fit of the valve body.

The motor block 10 is provided with an inlet 26 for connecting a compressed air line thereto. From the inlet 26 the compressed air is conducted through a passageway 27 to valve structure 28 including a valve housing 28a in threaded engagement with the motor block 10, a movable operating knob 29, a spring 30 and a ball 31. The valve housing 28a is provided with conventional seals at 28b and 280. When compressed air is supplied to the inlet 26, the ball 31 will be moved into an airtight position against its seat 32. For the com pressed air to be conducted further through the passageways 33 and 34, the operating knob 29 is moved inward, causing a projection 35 thereon to move the ball aside. The passageway 34 opens directly into the cylinder 11 and the conical-shaped portion 22 p of the slide serves as a guiding surface for the compressed air. A piston 36 moves forward and backward in the cylinder 11 and coacts with a pump rod 37 which moves in a pump housing 38. The latter is threaded into the pump block 12 so that both the pump housing and the pump rod can be easily replaced. The piston 36 is returned to the position shown in the drawing by structure including a spring 39 and a washer 40 against which the spring bears. The pump rod 37 has an end head 41 which is loosely connected to the piston 36 and bears against its inner side.

The lower part of the cylinder 11 is in communication with the atmosphere through an opening 42. When the piston 36 is in its lowermost position, the upper portion of the cylinder space is in communication with the upper part of the bore 13 through a conduit 43. Further, when the valve body 14 has moved downward from the position shown in the drawing, the cylinder space also will be in communication with the atmosphere through a cavity 44 in the motor block 10, the space and the channel 21. In such lower position of the valve body 14, the passageway 34 at the same time will be closed. The upper ends of the conduit 43 and the bore 13 are closed by a cover 45 which can be made of a suitable plastic material.

The pump block 12 is provided with valve structure 46 of the same construction as the valve structure 28 shown in the drawing and described above. The valve structure 46 is associated with a check valve which includes a ball 47, a spring 48 and a seat 49. The block 12 is also provided with a second check valve which includes a ball 50, a spring 51 and a seat 52. The latter is formed in a plug 53 having a passageway 54 in communication with a passageway 55 formed in the block 12. The block 12, in addition, is formed with passageways 56 and 57 and a connection 58. When the passageways 55 and 56 are connected to a source of supply of liquid, such as a body of oil, for example, such liquid can be discharged under pressure from the connection 58.

The apparatus described above operates in the following manner. When a source of supply of compressed air is connected to the inlet 26 and the operating'knob 29 is held in its in or operative position, compressed air will flow through the passageway 34 into the cylinder space and impart downward movement to the piston 36. When the piston has moved to its lowermost position, communication is established between the cylinder space and the bore 13 and compressed air will flow through the duct 43 and act on the valve body 14. Since the diameter of the seal 18 is greater than the diameter of the slide 15, downward movement will be imparted to the valve body. When this occurs the passageway 34 will be closed and compressed air no longer will flow to the cylinder 11. Immediately after or at the same time that the passageway 34 is closed, the slide 15 will open the connection between the cavity 44 and the space 20. In this way compressed air will be discharged to the atmosphere through the channel 21. When this occurs the air pressure acting on the piston 36 will be reduced and the piston will be moved back by the spring 39 to its position illustrated in the drawing. At the same time the piston 36, which is spring biased upward by the thrust head 23, will impart upward movement to the valve body 14 to return the latter to its position illustrated in the drawing. This course of action will be repeated all of the time the operating know 29 is held in its in" or operative position.

The washer 40 coacts with the pump rod 37 in such manner that the latter will follow the up and down movements of the piston 36. During the downward movements of the piston liquid in the space 59 will be forced from the pump block 12 through the seat 49, the passageway 57 and the connection 58. During the upward movements of the piston liquid will be drawn into the space'59 through the passageways 55 and S4 and the opening provided at the seat 52 with the ball 50 in its unseated position.

When the operating knob 29 is released, compressed air no longer will be supplied to the motor and at the same time the pumping action will stop. Under these conditions the pressure at the connection 58 possibly can remain because the passageway 57 will be closed by the valve structure 46 and the check valve 47. When the valve structure 46 now is opened by pressing its operating knob 46a inward, such liquid under pressure in the connection 58 will return to the source of-supply through the passageways 57 and 56.

lclaim:

1. In a compressed-air pump,

a. a compressed-air motor comprising a cylinder having a space and a block serving as a head therefor,

said block having a bore,

. a piston for said cylinder which is movable forward and backward in the space,

c. valve means comprising a valve body movable in said bore between first and second positions,

. structure including passageways only in said block for supplying compressed air from a source of supply to the piston of said motor in the firstposition of said valve body and for establishing communication between the cylinder space and atmosphere in the second position of said valve body,

e. said structure being so constructed and arranged that compressed air is supplied to said piston when it is in one position in the cylinder space and said valve body is in its first position and such supply of compressed air to said piston through said passageways ceases when said valve body is in it second position,

f. said valve body, responsive to compressed air supplied to said motor when said body is in its first position, being movable therefrom to its second position, and i g. said valve body comprising a rod having an intermediate portion and a first end portion removed from said piston and a second end portion nearer to said piston than said first end portion, said first end portion including resilient means in sealing engagement with said bore and said second end portion being solid and in sliding engagement with at least a part of said bore and said intermediate portion having a smaller cross-sectional area than that part of said bore with which it coextends.

2. Apparatus as set forth in claim 1 in which-said block has a first passageway forming a part of said structure which, in the first position of said valve body, serves to supply compressed air from the source of supply directly into said cylinder, said block also having a second passageway establishing communication between that portion of said bore occupied by the intermediate portion of said valve body and the atmosphere.

3. Apparatus as set forth in claim 1 in which said second end portion of said valve body has a flat surface and said block has a cooperating flat surface at said bore which serves as a seat for the flat surface of said valve body in its first position.

4. Apparatus as set forth in claim 1 in which said passageways include at least one cavity in said block at a region thereof nearest to said piston, and said one cavity forming at least a part of said passageway which establishes communication between the cylinder space and the atmosphere and includes that part of said bore coextensive with the intermediate portion of said valve body when it is in its second position.

5. Apparatus as set forth in claim 4 in which said structure is so constructed and arranged that the second end portion of said valve body, during its movement from its first to its second positions, initially reduces the supply of compressed air to said piston and subsequently functions to establish communication between said cylinder space and the atmosphere through said passageway which includes said one cavity.

6. Apparatus as set forth in claim 5 in which said one cavity is disposed in said block at the portion of said bore in which the intermediate portion of said valve body is disposed, said block having a passageway extending from said one cavity to an exterior surface thereof.

7. Apparatus as set forth in claim 5 in which the second end portion of said valve body, during its movement from its first to its second positions, initially shuts off the supply of compressed air to said piston and thereafter functions to establish communication between said cylinder space and the atmosphere.

8. Apparatus as set forth in claim 1 in which the second end portion of said valve body includes a conical-shaped end section and a thrust head which is fixed to and carried by said end section and faces said piston, said conical-shaped end section functioning to guide compressed air supplied to said motor through at least one passageway in said block in the first position of said valve body. I

9. Apparatus as set forth in claim 8 in which said conical-shaped end section deflects compressed air from said one passageway toward said piston in a direction substantially parallel to its forward and backward movement in said cylinder space.

10. Apparatus as set forth in claim 1 in which said resilient means and said valve body comprise plastic material.

11. Apparatus as set forth in claim 10 in which said resilient means includes a conical-shaped collar in sealing engagement with said bore and an integrally formed hollow bushin fixed to the first end portion of said rod. 12. Appara us as set forth in claim 11 In which the first end portion of said rod is formed with ridges at its periphery which are axially spaced from one another, and said hollow bushing of said resilient means being anchored on said rod between said axially spaced ridges. 

1. In a compressed-air pump, a. a compressed-air motor comprising a cylinder having a space and a block serving as a head therefor, said block having a bore, b. a piston for said cylinder which is movable forward and backward in the space, c. valve means comprising a valve body movable in said bore between first and second positions, d. structure including passageways only in said block for supplying compressed air from a source of supply to the piston of said motor in the first position of said valve body and for establishing communication between the cylinder space and atmosphere in the second position of said valve body, e. said structure being so constructed and arranged that compressed air is supplied to said piston when it is in one position in the cylinder space and said valve body is in its first position and such supply of compressed air to said piston through said passageways ceases when said valve body is in its second position, f. said valve body, responsive to compressed air supplied to said motor when said body is in its first position, being movable therefrom to its second position, and g. said valve body comprising a rod having an intermediate portion and a first end portion removed from said piston and a second end portion nearer to said piston than said first end portion, said first end portion including resilient means in sealing engagement with said bore and said second end portion being solid and in sliding engagement with at least a part of said bore and said intermediate portion having a smaller crosssectional area than that part of said bore with which it coextends.
 2. Apparatus as set forth in claim 1 in which said block has a first passageway forming a part of said structure which, in the first position of said valve body, serves to supply compressed air from the source of supply directly into said cylinder, said block also having a second passageway establishing communication between that portion of said bore occupied by the intermediate portion of said valve body and the atmosphere.
 3. Apparatus as set forth in claim 1 in which said second end portion of said valve body has a flat surface and said block has a cooperating flat surface at said bore which serves as a seat for the flat surface of said valve body in its first position.
 4. Apparatus as set forth in claim 1 in which said passageways include at least one cavity in said block at a region thereof nearest to said piston, and said one cavity forming at least a part of said passageway which establishes communication between the cylinder space and the atmosphere and includes that part of said bore coextensive with the intermediate portion of said valve body when it is in its second position.
 5. Apparatus as set forth in claim 4 in which said structure is so constructed and arranged that the second end portion of said valve body, during its movement from its first to its second positions, initially reduces the supply of compressed air to said piston and subsequently functions to establish communication between said cylinder space and the atmosphere through said passageway which includes said one cavity.
 6. Apparatus as set forth in claim 5 in which said one cavity is disposed in said block at tHe portion of said bore in which the intermediate portion of said valve body is disposed, said block having a passageway extending from said one cavity to an exterior surface thereof.
 7. Apparatus as set forth in claim 5 in which the second end portion of said valve body, during its movement from its first to its second positions, initially shuts off the supply of compressed air to said piston and thereafter functions to establish communication between said cylinder space and the atmosphere.
 8. Apparatus as set forth in claim 1 in which the second end portion of said valve body includes a conical-shaped end section and a thrust head which is fixed to and carried by said end section and faces said piston, said conical-shaped end section functioning to guide compressed air supplied to said motor through at least one passageway in said block in the first position of said valve body.
 9. Apparatus as set forth in claim 8 in which said conical-shaped end section deflects compressed air from said one passageway toward said piston in a direction substantially parallel to its forward and backward movement in said cylinder space.
 10. Apparatus as set forth in claim 1 in which said resilient means and said valve body comprise plastic material.
 11. Apparatus as set forth in claim 10 in which said resilient means includes a conical-shaped collar in sealing engagement with said bore and an integrally formed hollow bushing fixed to the first end portion of said rod.
 12. Apparatus as set forth in claim 11 in which the first end portion of said rod is formed with ridges at its periphery which are axially spaced from one another, and said hollow bushing of said resilient means being anchored on said rod between said axially spaced ridges. 